The present invention relates to snowplough blades, that is, apparatuses carried by suitable machines (agricultural tractors, trucks) in order to remove the snow from the ground.
The machines are operated to adjust their snow removing front part according to the contingent needs and the characteristics of the road paths (roads with reduced width, with one or more lanes, etc.)
Different types of snowplough blades with variable width are known to those experts in the field, and substantially they include: a first stationary blade body, carried by a frame for suspension and coupling to a respective vehicle. The first stationary blade body includes, situated in its lower part, shock absorbers for coupling with a flexible scraper which bends with respect to the first blade body in the direction opposite to the blade forward movement in case of collisions with obstacles or irregularities of the road surface; a second blade body, connected with its rear part to the first blade body, by means of mutual coupling, sliding and moving with respect to the latter between an inner retracted position, in which the front of the snowplough blade is formed only by the first blade body, and an extreme advanced position, in which the front of the blade is formed by the first and second blade bodies, arranged abreast, with the second blade body situated on the right with respect to the vehicle forward movement direction and having, likewise in its lower part, shock absorbing means for coupling with a related scraper.
In particular, the Utility Model Application no. BO2002U 000069, of the same Applicant, is distinguished by the fact that the first stationary blade body forms, on its rear surface, facing the second moving blade body, a shoulder for supporting mutual coupling means, so as to keep the second blade body at a distance with respect to the first blade, to delimit a free space.
When the second blade body is in the inner retracted position, the scraper of the first blade body moves into the free space while bending because of collision with obstacles or irregularities of the road surface.
In spite of the many technical-functional advantages of the above mentioned solution, some drawbacks must be pointed out, with reference to the enclosed Figures related to prior art, in which FIGS. 1A, 1B, 1C, 1D are corresponding plan views of the snowplough blade in as many significant configurations, and FIG. 4 is a scheme of a snowplough machine, having a third lateral blade in work configuration.
The snowplough blade AL includes: a first blade body AL1, supported by a structure AS for suspension and coupling with a respective operative vehicle (not shown); and a second blade body AL2, connected to the rear part of the first blade body AL1, parallel thereto, by means of mutual sliding coupling means, and moved with respect to the first body between an inner retracted position (FIGS. 1A, 1C) and an extreme advanced position (FIGS. 1B, 1D) by operation of hydraulic jack, interposed between the structure AS and the second blade body AL2.
As it can be noted, the space occupied by the suspension and coupling structure AS connected to the first blade body AL1 defines a limit to the width of the second blade body AL2, when it is in the retracted position.
This fact limits also the maximum width of the snowplough blade AL as a whole, also considering that the maximum width of the first blade body AL1 is related to the vehicle width, for space and safety reasons.
Another width limit of the second blade body AL2 is imposed by practical reasons: actually, the vehicle driver can find it difficult to estimate the real dimension of the second blade body AL2 in extreme advanced position (see for instance FIG. 1C) during the snow clearing, due to the his unfavorable position in the cabin (conventionally on the left).
This obviously results in a high risk of collisions and damages to the objects out of the road.
Another disadvantage of this configuration results from a limited, or lacking, utility of the lateral snowplough blade, situated on the right side (with respect to the forward movement direction) of some vehicles, when the second blade body AL2 is brought to the extreme advanced position (see FIG. 4).